Pressure-sensitive copying paper

ABSTRACT

PRESSURE-SENSITVE COPYING PAPERS CONTAINING A FLUORAN DERIVATIVE HAVING THE FOLLOWING GENERAL FORMULA   3-(R1-N(-R2-),7-(R4-N(-R3-)SPIRO(PHTHALAN-1,9&#39;&#39;-XANTHENE)   WHEREIN R1 AND R2 EACH REPRESENTS AN ALKYL GROUP HAVING FROM 1 TO 5 CARBON ATOMS; WHEREIN R3 REPRESENTS A HYDROGEN ATOM, AN ALKYL GROUP HAVING FROM 1 TO 5 CARBON ATOMS, OR A BENZYL GROUP; AND WHEREIN R4 REPRESENTS AN ARYL GROUP ARE DISCLOSED.

United States Patent U.S. Cl. 11736.2 7 Claims ABSTRACT OF THEDISCLOSURE Pressure-sensitive copying papers containing a fluoranderivative having the following general formula a R R2 7 3 4, wherein Rand R each represents an alkyl group having from 1 to 5 carbon atoms;wherein R represents a hydrogen atom, an alkyl group'having from 1 to 5carbon atoms, or a benzyl group; and wherein R represents an arylgroupare disclosed. .7 r

BACKGROUND OF THE INVENTION (1) Field of the invention The presentinvention relates to a pressure-sensitive copyingpaper and moreparticnlarly'it is concerned with a pressureesensitive copying paper inwhich a fluoran de- M rivative is used as a color former 1 H I (2)Description of the priorart.

Ordinary pressure-sensitive copying papers-meromposed of an upper sheetprepared by applying to-asupport, such as paper, fine .capsules ormicrocapsules con;

taining therein an organic solvent solution of a substanpapers are'composedof the aforesaid upper sheet, the

under sheet, and further an intermediate sheet having on ice In thepractice of the combination of the upper sheet and the under sheet orthe combination of the upper sheet, the intermediate sheet, and theunder sheet, the papers are stacked so that the microcapsule layercontacts the solid acid layer and with localized pressure, themicrocapsules at the pressurized portions are ruptured causing thereaction of the color former and the solid acid to form a distinctcolor. Also, when a pressure-sensitive copying paper of the type havingthe microcapsules and the solid acid on one surface of a support islocally pressurized, the microcapsules are ruptured to form a distinctcolor. These pressure-sensitive copying papers are Well known, havingbeen described in U.S. Pat. 2,712,507, U.S. Pat. No. 2,730,457 and U.S.Pat. No. 2,730,456. I

An object of the present invention is to provide a pressure-sensitivecopying paper having a high light fastness and capable of forming ablack, a dark green, or a dark grey color using only a single colorformer.

Another object of the present invention is to provide apressure-sensitive copying paper capable of being colored a desiredcolor such as blue black using the color former of this inventiontogether with a conventional color former and which is neitherdiscolored nor faded by light.

SUMMARY OF THE INVENTION The present invention relates to apressure-sensitive paper having a layer of microcapsules containing as acolor former a fluoran derivative represented by the general formula,

wherein R and R each represents an alkyl group having from 1 to 5carbon'atoms; wherein R represents a hydrogen atom, an alkyl grouphaving from'l to 5, carbon atoms, or a benzyl group; and whereinRfrepresents an one surface thereof a layer of microcapsules containingthe color former and on the. opposite surface the layer of the solidacid. In another typeof pressure-sensitive.

copying paper, the microcapsules containing the color former and thesolid acid are applied to the same surface of a support, such as paper.

aryl group.

DETAILED DESCRIPTION OF THE I INVENTION 7 1 I The inventors reportedpreviously a fluoran derivative having the aforesaid formula in which,however, R is not an aryl group but is ia'hydrogen atom, an alkyl grouphaving from l to 5 carbon atoms or a benzyl group, while R ,R2 and R arethe same as described aboye..The fluoran derivative previously found asa color former is black when contacted with a solid acid but has thedisadvantage that the color former is changed to a red color whenexposed directly to sun light.

In the present invention, such disadvantages are improved by using thefluoran derivative of the above formula. Typical examples of thecompounds represented by the above formula are as follows:

Color General formula former number R1 Ra Ra R4 Chemical name 1 02E; 02EH G 3-diethylamino-7-anillno-fluoran.

2 CH; CH; CH: Q 3-dimethylamino-7-(N-methylanilino)-fluoran.

3 H; CzHs H I v Q OH 3-diethylamino-7-(para-toluidino)-fluoran.

4. cam 0,11, H 3-diethyla1nino-7-(n1eta-toluidino )dluoram a CHI I v Y i5 01H; 0,11 CH; a-diethirlamlnod-(N -niethylanillno)-fluoran. I

e can; can, H a d-diethylamino-F(ortho-toluidlno)-fluoran.

' Y CHAL 3 7.; 0E5 02H: H 3-diethylamino-7-(meta-xylldino)-fluoran.'

I v v s CH8 Y'Y'SN s. 0:115 0211. H3-diethylarnino-l-(ortho-anisidino)-tluoran.

OCH L i. 7' I: 9 02H; 02H; Q Q3-diethylamino-7-(N-lienzrlanilino)-flu0ran. 1o CzHu (3H; CH, @00113-dlethylamino-7-(N-IuethyLpara-anisidino)-fluoran.

v a 11 03H; (32115 H @0011 3-diethylam1no-7-(para-anisldino)-fluoran. 1202H; Iso-CzHz n-olm Q 1'3-N-ethyl-N-isopropyl-amino-7-(N-butyl-anilino)-fluoran.

The color former used in the present invention can be prepared by thefollowingnianner. I u v That is, general methods for preparing the colorformers V wherein R1, R2, R3 and R4 are as above rdefined one a of thepresent invention are as follows. of Intermediate A,o-(4-dialky1amino-Z-hydroxybenzoyl) RI 'benzoic acid, and one mole ofIntermediate 'B', p-N-arylaminophenoLare dissolved in 10-20 moles ofsulfuric acid r I v and thersystem is reacted for 2-8 hours at 80-100 C.R4 v After the reaction is over, the reaction product is poured I into alarge proportion of ice'wa'ter and the sulfuric acid in "thereactionproduct is neutralized with an aqueous v v alkali solution, such as anaqueous solution of sodium hy- (rnteymediate B) droxide; to convert thesystein into a slightly alkaline state.

1, The product thus precipitated'is extracted from the aqueous phase"toluenegfand the like, concentrated and dried. Thecr'ude product thusobtained is then recrystal- Ra I lized. fron1 benzene, ethenrethanol or.a mixture thereof.

The color, formers of theapresent invention can be prepared by thefollowing "method generally; the method 5Bin h wver',' applicable toonly the case of preparing a color former having the aforesaid generalformula wherein R is a hydrogen atom;

(Intermediate B) wherein R R and R are as above defined and R representsan alkyl group having 1 to 5 carbon atoms or an aryl group.

1 One mole of o-(4-dialkylamino-2-hydroxybenzoyl)-benzoio acid is causedto react with one mole of p-(N-acyl- N-arylamino)-phenol in concentratedsulfuric acid for 8-50 hours at 30l00 C. and the reaction product ispouredin a large proportion of ice-cooled water to form a precipitate,which is recovered and heated in diluted sulfuric acid or dilutedhydrochloric acid for 3-6 hours at 90-100" C. to liberate the acyl group(COR'). By neutralizing the product with an aqueous alkali solution, thcolor former desired is obtained.

Intermediate A used as a starting material for preparing the colorformer of this invention, can be prepared according to a known method asdescribed in Fliedlendar, vol. 4, page 260, by refluxing under heatingfor a few hours 1 mole of meta-dialkylamino-phenol and 1 mole ofphthalic anhydride in a solvent such as toluene.

Intermediate B having thewaforesaid general formula, wherein R ishydrogen atom, can be prepared as product (11) below by a known methodas described in Chemical Abstracts, 52, 718421, by heating an arylamine(I), hydroquinone, and cone. sulfuric acid to cause a dehydration andcondensation reaction.

wherein R represents an aryl group.

Furthermore, Intermediate B having the above-described general formulawherein R is an alkyl group having from ltto 5 carbon atoms or a benzylgroup can be prepared by. alkylating or benzylating compound (H) shownabove in a conventional manner.

Moreover, Intermediate B shown above can be prepared by acylatingcompound (II) in a conventional manner.

Preparation of the color formers of the present invention is furtherillustrated by theexamples given hereinafter.

6 PREPARATION EXAMPLE 1 Preparation of color former No. 1: Color formerNo. 1 was prepared by causing the dehydration reaction of IntermediateA, wherein R is C H and R is C H o-(4-diethylamino-2-hydroxybenzoyl)benzoic acid, and Intermediate B, in which R is H and R is a phenylgroup, p-anilinophenol, in concentrated sulfuric acid by the sameprocedure as in the general method described above. The product wasrecrystallized from a benzene-ethanol mixture to provide white crystalsof the color former having a melting point of 182-185 C.

PREPARATION EXAMPLE 2 Preparation of color formers 2-12: The sameprocedure as used in Preparation Example 1 was followed usingIntermediate A and Intermediate B corresponding to each color former toprovide the color former desired.

The melting points of the color formers thus prepared and the visibleabsorption of the color formers in acetic acid are shown in the tablebelow.

PREPARATION EXAMPLE 3 Preparation of color formers Nos. 1, 3-4, and 6-8by the second method: By applying the second method described using 1mole of o-(4-diethylamino-2-hydroxybenzoyl)benzoic acid and 1 mole ofp-(N-acetanilino)- (or N-benzoylanilino)phenol, color former No. 1 wasalso obtained. The crystals of the color former had the same meltingpoint, same infrared spectrum, and same visible absorption spectrum inacetic acid as those of the color former No. 1 prepared in PreparationExample 1.

Maximum Color Melting absorpt1on(m ormer Solvent for pom irumberrecrystallization 0.) x1 A2 446 605 450 605 451 616 447 610 451 605 450601 451 605 455 600 452 606 456 596 451 596 455 610 1 Amorphous solid.

The color formers Nos. 3, 4, 6, 7 and 8 were also prepared in the samemanner using the corresponding startlng materials. r For preparing thepressure-sensitive copymg paper of the present invention using the colorformers described above, and/or conventional color formers such ascrystal violet lactone, leuco methylene blue, malachite green lactone,rhodamine B lactram, and the like, the known method disclosed in, forexample, the specification of US. Pat. Nos. 2,548,366, 2,800,457 and2,800,458, that is, a method of preparing microcapsules utilizing aco-acervation technique can be employed. However, since the feature ofthe present invention is in the use of the color former and the functionof the pressure-sensitive copying paper of the present invention is notinfluenced by the method of preparing the pressure-sensitive copyingpaper employed, other methods than above described can also be employedin the present invention.

The proportion of the color former used usually ranges from 1 to 10% byWeight to the amount of the oily solvent employed.

Also, as the electron-acceptive solid acid, suitable materials areclays, such as acid clay, active clay, attapulgite, zeolite orbentonite; organic acid maerials, such as succinic acid, tannic acid,gallic acid or pentachlorophenol resins, phenol compounds and phenolicresins. As the organic solvent for dissolving the color former, suitablesolvents are chlorobenzene, chlorinated paraflins, and diphenylchloride.

The pressure-sensitive copying paper of this invention is substantiallycolorless before color formation and when the copying paper is locallypressed together with the layer of the solid acid, the color formingreaction occurs instantaneously to form a black, drak green or dark greycolor. That is, the color thus formed absorbs the entire visible regionof from about 410 ru to about 650 m and also has absorption in thespectral region of from about 350 Inn to about 420 mp. This makes itpossible to copy on a diazotype light-sensitive paper. Furthermore, thepressure-sensitive copying paper has excellent light fastness ascompared with conventional ones.

Now, the invention will be explained by the following examples in whichthe pressure-sensitive copying papers using the above-mentioned colorformers shown by the general formula are illustrated.

Example l.-Three grams of each of the color formers No. 1 to No. 12 wereprocessed as follows. The color former was dissolved in 100 g. ofdiphenyl trichloride and the solution was added to a solution of 20 g.of gum arabic dissolved in 160 g. of water and then the mixture wasemulsified. Then, a solution of 20 g. of acid-treated gelatin in 160 g.of water was added to the resultant emulsion, the pH of the system wasreduced to 5 by adding acetic acid with stirring constantly, and then500 g. of water was added to cause co-acervation, whereby a concentratedgelatin-gum arabic film was formed around an oil drop having dissolvedtherein the color former. Thereafter, the pH of the system was furtherreduced to 4.4 and then 4 g. of 37% formalin was added as a hardeningagent. The above procedures were all conducted at a temperature of 50 C.Thereafter, the temperature of the system was lowered to C. for gellingthe concentrated liquid film around the oil drop and further the pHthereof was increased to 9 for improving the hardening effect. Then, byallowing the system to stand for a few hours, the capsulation wasfinished. The capsule-containing solution thus prepared was applied to apaper by roll coating or air-knife coating and dried to provide thepressure-sensitive copying paper (upper sheet). The upper sheet wasplaced on a clay-coated sheet (under sheet prepared by applying theabove-described active clay to a paper) and they Were locallypressurized by handwriting. Thereby, the following color was instantlyformed on the clay-coated paper.

That is, color formers No. 1, No. 6 and No. 7 were colored black; colorformers No. 2, No. 3, No. 4, No. 5, N0. 9, and No. 10 were colored darkgreen, and color formers No. 8 and No. 11 were colored dark grey. Also,the dyes thus colored were not faded when they were exposed to sun lightfor a long period of time and wetted with water or glycerine. Also, whenthe upper sheet having the layer of the microcapsules containing thecolor former was heated to 100 C. for 20 hours and exposed to sunlightfor a long period of time, the color forming ability of the copyingpaper was not degraded. In other words, the light fastness, waterresistance, and heat resistance of the pressure-sensitive copying paperof this invention before color forming and after color forming weresufliciently high from a practical standpoint when the copying paper wasstored for a long period of time.

Example 2.--The same procedure as used in Example 1 was followed exceptthat 1 g. of the color former No. 1, 1 g. of the color formed No. 3, 0.5g. of Malachite Green Lactone, and 0.5 g. of benzoyl leucomethylene bluewere used as a mixture thereof instead of the color former in theExample 1. The results were that the clay-coated paper was colored blueblack.

What is claimed is:

1. A pressure-sensitive copying paper comprising a support having coatedthereon a layer of microcapsules containing at least one fluoranderivative having the following general formula,

wherein R and R each are an alkyl group having from 1 to 5 carbonatoms,.wherein R is selected from the group consisting of a hydrogenatom,*an alkyl group having from 1 to 5 carbon atoms, and a benzylgroup, and wherein R is an aryl group. v

2. The pressure-sensitive copying paper as claimed in claim 1 whereinsaid fluoran derivative is a member selected from the group consistingof 3 -diethylamino-7-anilino fiuoran,

3 -dimethyla mino-7- (N-methylanilino) -fluoran, 3-diethylamino-7-(p-toluidino) -fluoran,

3 -diethylamino-7- m-toluidino -fluoran, 3-diethylamino-7-(N-methylanilino) -fluoran, 3-diethylamino-7- o-toluidino) -fluoran,

3 -diethylamino-7- m-xylidino) -fluoran, 3-diethylamino-7- (o-anisidino)-fluoran,

3 -diethylamino-7- (N-b enzylanilino) -fluoran, 3-diethylamino-7-(N-methyl-p-anisidino -fiuoran, 3 -diethylamino-7- (p-anisidino)-fluoran, and

3 -N-ethyl-N-isopropylamino-7- N-butyl anilino) -fiuoran.

claim 1 wherein said fluoran derivative is capable of forming a distinctcolor when contacted with a material selected from the group consistingof acid clay, active clay, attapulgite, zeolite, phenolic compounds andphenolic resins. 4. The pressure-sensitive copying paper as claimed inclaim 1 wherein said fluoran derivative is used together with at leastone color former selected from the group consisting of crystal violetlactone, leuco methylene blue, malachite green lactone and rhodamine Blactam.

5. A pressure-sensitive copying paper comprising an upper sheet havingcoated thereon a layer of microcapsules containing at least one fluoranderivative having the following general formula, 3 v

wherein R and R each are an alkyl group having from 1 to 5 carbon atoms,wherein R is selected from the group port having coated on the samesurface thereof two layers,-

one of said layers comprising microcapsules containing at least onefluoran derivative having the following general formula,

3. The pressure-sensitive copying-paper as claimed in the UNITED 7. Thepressure-sensitive copying paper as claimed in claim 6 wherein saideleetro accepting material is a member selected from the groupconsisting of acid clay, active clay, attapulgite, phenol compounds andphenolic resins.

References Cited STATES PATENTS Kimura et al 117--36.8 Kimura et a1.117-362 Katayama et a1. 117-362 MURRAY KATZ, Primary Examiner US. Cl.X.R.

